Double loop lasso with single puller wire for bi-directional actuation

ABSTRACT

A catheter has a distal assembly with at least one loop, if not two, with ring electrodes. The distal assembly has an elongated support member covered by an extruded form having two lumens, one sized for nonslip tight fit with the support member. A single continuous puller wire for bidirectional deflection is pre-bent into two long portions and a U-shape bend therebetween. The U-shape bend is anchored at a distal end of a deflectable section which is reinforced by at least one washer having at least two holes, each hole axially aligned with a respective lumen in the deflectable section. Each hole is centered with a lumen so that each puller wire portion therethrough is straight and subjected to tensile force only. A proximal end of the support member is flattened and serrated to provide a better bonding to the distal end of the deflectable section.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of and claims priority to and thebenefit of U.S. application Ser. No. 13/732,283 filed Dec. 31, 2012,issued as U.S. Pat. No. 9,050,010, the entire content of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an improved ablation catheter that isparticularly useful for mapping or ablating in a tubular region of ornear the heart.

BACKGROUND OF THE INVENTION

Electrode catheters have been in common use in medical practice for manyyears. They are used to stimulate and map electrical activity in theheart and to ablate sites of aberrant electrical activity. Atrialfibrillation is a common sustained cardiac arrhythmia and a major causeof stroke. This condition is perpetuated by reentrant waveletspropagating in an abnormal atrial-tissue substrate. Various approacheshave been developed to interrupt wavelets, including surgical orcatheter-mediated atriotomy. Prior to treating the condition, one has tofirst determine the location of the wavelets. Various techniques havebeen proposed for making such a determination, including the use ofcatheters with a distal assembly that is adapted to measure activityand/or ablate within a pulmonary vein, coronary sinus or other tubularstructure about the inner circumference of the structure. One suchdistal assembly has a tubular structure comprising a generally circularmain region generally transverse and distal to the catheter shaft andhaving an outer circumference of about 360 degrees and a generallystraight distal region distal to the main region. The tubular structurecomprises a non-conductive cover over at least the main region of thedistal assembly. A support member having shape-memory is disposed withinat least the main region of the mapping assembly. A plurality ofelectrode pairs, each comprising two ring electrodes, are carried by thegenerally circular main region of the distal assembly.

In use, the electrode catheter is inserted into a guiding sheath whichhas been positioned a major vein or artery, e.g., femoral artery, andguided into a chamber of the heart. Within the chamber, the catheter isextended past a distal end of the guiding sheath to expose the distalassembly. The catheter is maneuvered through movements that includedeflection of a distal portion of the catheter so that the distalassembly is positioned at the tubular region in the heart chamber. Theability to control the exact position and orientation of the catheterand also the configuration of the distal assembly is critical andlargely determines how useful the catheter is.

Deflection and steering of the catheter is typically accomplished by acontrol handle that houses deflection mechanism responsive to anactuator provided on the control handle. A puller wire extends throughthe catheter in a lumen along one side and the deflection mechanismdraws on the puller wire proximally to deflect the catheter toward thatside. Bi-directional deflection is accomplished by two opposing pullerwires, each along one side of the catheter. By manipulating the actuatorin one selected direction or another, the deflection mechanism acts on aselected puller wire to deflect the catheter along that side of thecatheter. The distal end of each puller wire is typically anchored bymeans of a crimped ferrule soldered to a tip dome or a T-bar adhesivebonded to a diamond cut groove in a side wall of a tubing. However,these anchoring means can be offset from the lumens thus subject thepuller wire to combined stresses of bending and shear along with tensilestresses. Moreover, tip deflection can also be skewed and off planereducing predictability of desired deflection.

Another issue with catheters arises from free play and slippage betweenthe support member of the distal assembly and the nonconductive coverwhich reduces the accuracy of the mapping and ablation procedures.Furthermore, the support member can also dislodge or detach from thecatheter when the distal assembly is subjected to repeated and/orexcessive contact forces. Additionally, repeated and/or excessivecontact forces can also damage components, such as a location sensor,that are near where the support member is anchored to the catheter.

Accordingly, there is a desire for a catheter that provides bi-directiondeflection in a manner that avoids bending and shearing stresses on thepuller wires and a catheter that avoids skewing or off-plane deflection.There is also a desire for a catheter that minimizes micro-movementsbetween the support member and the cover during mapping and ablation anda catheter with a distal assembly that is reliably mounted to thecatheter.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter having a distal assemblymounted on its distal end. The distal assembly has a generally circularmain portion, having at least one loop, if not two loops with an outerloop and an inner loop, each of which carries a plurality of ringelectrodes adapted for mapping and/or ablation. The generally-circularmain portion is generally transverse to a longitudinal axis of thecatheter. The loops of the generally-circular main portion may liewithin one plane or one loop may be more distal than another loop toform a spiral or helical pattern.

In one embodiment, the catheter has an elongated tubular catheter bodywith at least one lumen, a deflectable intermediate section with atleast two off-axis lumens, and a distal assembly with a tubularstructure having a generally straight proximal region attached to thedeflectable intermediate section and a generally circular main regiongenerally transverse and distal to the proximal region. The distalassembly has an elongated rod-like support member with shape memoryextending through the length of the distal assembly. An extrudednon-conductive cover covers the support member which extends through afirst lumen of the cover. The first lumen is sized to provide a tight orinterference fit with the support member to minimize free play andmicro-movements between the cover and the support member. Lead wires forelectrodes carried on the distal assembly extend through a second lumenformed in the cover. The cover is constructed of a material that readilyconforms to the shape and configuration of the support member withoutheat treatment.

In one embodiment, a single continuous puller wire extends through thecatheter to effectuate bi-directional deflection of the deflectablesection. The deflectable section has at least two off-axis lumens forthe puller wire which is pre-bent into a U-shape, with a mid-portion andtwo proximal end portions. At a distal end of the deflectableintermediate section, the mid-portion straddles the two off-axis lumens,each of which receives a proximal end portion that extends toward thecontrol handle. To reinforce the distal end of the deflectable sectionagainst compression forces when a proximal end portion of the pullerwire is acted on for deflection, at least one washer is provided betweenthe mid-portion and the distal end. The washer has at least two holes,each axially aligned with a respective off-axis lumen of the deflectablesection. Each hole is centered relative to the respective lumen so thateach proximal end portion of the puller wire extending through a washerhole and an off-axis lumen is generally parallel with the longitudinalaxis of the catheter and thus subjected to tensile forces only withminimal shear. Advantageously, bi-directional deflection effectuated inthis manner is more predictably on-plane with less skewing.

In one embodiment, the support member of the distal assembly is anchoredat its proximal end in a connector section extending between thedeflectable intermediate section and the distal assembly. The connectorsection has a central lumen filled with adhesive to form an adhesivevolume in which a proximal end of the support member is anchored. Tothat end, a proximal end of the support member is flattened to provide amore planar form, with more bonding surface. The proximal end is alsoserrated to provide an irregular bonding surface. Accordingly, theproximal end potted in the adhesive resists rotational and axialmovements that may otherwise loosen or detach the support member and thedistal assembly from the catheter.

In one embodiment, the each proximal end portion of the puller wire issurrounded by a compression coil that is flexible but resistscompression. Accordingly, a distal end of the compression coil defines alocation for initiation of a deflection curvature when the puller wireis acted on by deflection mechanism in the control handle. By providinga first compression coil with a longer length and a second compressioncoil with a shorter length, each proximal end portion of the puller wirehas a different deflection initiation location and hence a differentdeflection curvature to provide nonsymmetrical bi-directionaldeflection.

In one embodiment, a location sensor is potted in the adhesive volume ofthe connector section. The sensor has a housing that encloses at leastone sensing coil. The housing is generally encased in a protectivetubing which isolates the at least one sensing coil from the adhesivevolume and protects it from torsional and/or axial tension/compressionforces acting on the adhesive volume that may damage the sensor.

DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a catheter of the present invention, inaccordance with one embodiment.

FIG. 2 is a perspective view of a catheter body of the catheter of theFIG. 1, with portions of an outer wall and a stiffener broken away.

FIG. 2A is an end cross-sectional view of the catheter body of FIG. 2,taken along line A-A.

FIG. 3 is a perspective view of a deflectable intermediate section, aconnector section, and a distal assembly of the catheter of FIG. 1.

FIG. 3A is an end cross-sectional view of the deflectable intermediatesection of FIG. 3, taken along line A-A.

FIG. 3B is an end cross-sectional view of the connector section of FIG.3, taken along B-B.

FIG. 4 is a perspective view of an multi-lumened tubing of thedeflectable intermediate section of FIG. 3.

FIG. 5 is an exploded perspective view of a distal end of the tubing ofFIG. 4, along with two washers and a puller wire.

FIG. 6 a perspective view of the distal assembly, the connector sectionand a distal end of the deflectable intermediate section of FIG. 1.

FIG. 6A is an end cross-sectional view of the distal assembly of FIG. 6,taken along line A-A.

FIG. 7 is an end view of the distal assembly of FIG. 1.

FIG. 8 is an end view of a distal assembly according to anotherembodiment.

DETAILED DESCRIPTION

As shown in FIG. 1, a catheter 10 of the present invention comprises anelongated catheter body 12 having proximal and distal ends, adeflectable distal section 14 at the distal end of the catheter body,and a control handle 16 at the proximal end of the catheter body. Thecatheter also includes a distal assembly 17 that is mounted to aconnector section 15 at a distal end of the distal section 14. Thedistal assembly carries a plurality of electrodes 27 adapted for mappingand/or ablation.

With reference to FIGS. 2 and 2A, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e. bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. In thedisclosed embodiment, the catheter body includes at least an outer wall20 (e.g., of PEBAX or Pellethane). The outer wall 20 may include animbedded braided mesh of stainless steel or the like to increasetorsional stiffness of the catheter body 12 so that, when the controlhandle 16 is rotated, the catheter body 12 rotates in a correspondingmanner.

The outer diameter of the catheter body 12 is not critical, but may beabout 7 or 8 french. Likewise, the thickness of the outer wall 20 is notcritical, but is thin enough so that the central lumen 18 canaccommodate components including puller wires, multiple lead wires,cables and/or tubes. If desired the inner surface of the outer wall 20may be lined with a stiffening tube (e.g., of polyimide) (not shown) toprovide improved torsional stability and provide a reduction in shaftwaviness during catheter deflection when puller wire tension places thecatheter body in compression.

With reference to FIGS. 3 and 3A, the deflectable distal section 14comprises a shorter section of tubing 22 having a plurality of lumens,including at least first and second off axis diametrically-opposinglumens 30 and 31, each for a puller wire. In the illustrated embodiment,there are also at least third and fourth off-axis lumens 32 and 33, thelumen 33 for a cable 36 connected to a position sensor 34, and the lumen32 for lead wires 35 connected to the electrodes 27 carried on or nearthe distal assembly 17. Additional lumens may be provided asappropriate, such as for irrigation tubing to transport irrigation fluidto the distal assembly. The tubing 22 is made of a suitable non-toxicmaterial that is preferably more flexible than the catheter body 12. Onesuitable material is for the tubing 22 is braided polyurethane, i.e.polyurethane with an embedded mesh of braided stainless steel or thelike. The size of each lumen is not critical, but is sufficient to housethe respective component, such as lead wires, puller wires, cables andtubings.

The useful length of the catheter body 12, i.e. that portion that can beinserted into the body excluding the distal assembly 17, can vary asdesired. In one embodiment, the useful length ranges from about 110 cmto about 120 cm. The length of the distal section 14 is a relativelysmall portion of the useful length, and preferably ranges from about 3.5cm to about 10 cm, more preferably from about 5 cm to about 6.5 cm.

To attach the catheter body 12 and the distal section 14, a proximal endof the tubing 22 of the distal section 14 comprises a smaller outercircumferential notch 26, as shown in FIG. 4, that receives an innercircumferential surface of a distal end of the outer wall 22 of thecatheter body 12. The overlapping portions of the distal section 14 andcatheter body 12 are attached by glue or the like. If desired, a spacer(not shown) can be located within the catheter body between the distalend of the stiffening tube (if provided) and the proximal end of thedistal section. The spacer provides a transition in flexibility at thejunction of the catheter body and distal section, which allows thisjunction to bend smoothly without folding or kinking. A catheter havingsuch a spacer is described in U.S. Pat. No. 5,964,757, the disclosure ofwhich is incorporated herein by reference.

As shown in FIG. 3, the connector section 15 has a short cylindricalmember or tubing 23 with a central lumen 19 which houses the locationsensor 34 and anchors a proximal end of the distal assembly 17. Thetubing 23 may be constructed of any suitable material, for example,PEEK. To attach the distal section 14 and the connector section 15, adistal end of the tubing 22 of the deflectable section 14 comprises asmaller outer circumferential notch 28, as shown in FIG. 4, thatreceives an inner circumferential surface of a proximal end of thecylindrical member 23. The overlapping end of the tubings 22 and 23 areattached by glue or the like.

To effectuate deflection along the catheter body 12 for steering thecatheter body 12 and the distal assembly 17, a puller wire 24 extendsfrom the control handle 16 and through the entirety of the catheter body12 (FIG. 2). In accordance with a feature of the present invention, thepuller wire is a single continuous tensile member that providesbi-directional deflection, that is, deflection along two sides of thecatheter in opposing directions within a plane defined by the first andsecond lumens 30 and 31 of the tubing 22 of the distal section 14, asshown in FIG. 1. As also shown in FIG. 5, the puller wire 24 has a firstlongitudinal proximal portion 24A extending through the lumen 30, asecond longitudinal proximal portion 24B extending through the lumen 31,and a mid-short portion 24M that is formed between two opposing bends orcorners with angles at about 90 degrees. The longitudinal portions 24Aand 24B are parallel with a longitudinal axis of the catheter and theshort portion 24M is generally perpendicular thereto as it straddles thelumens 30 and 31 at the distal end of the tubing 22. Both proximal endsof the puller wire 24 are anchored in the control handle 16 asunderstood by one of ordinary skill in the art. Deflection in onedirection along one side of the catheter is enabled by a user'smanipulation of an actuator 54 on the control handle 16 (FIG. 1) whichdraws one or the other long portion 24A or 24B proximally. In thatregard, each long portion is surrounded by a respective compression coil25A, 25B (FIG. 2) that extends from a proximal end of the catheter body12 through the central lumen 18, into the respective lumen 30 or 31 ofthe distal section 14 (FIG. 3A) and terminates at predetermined distallocations A and B, respectively, (FIG. 1) along the length of the tubing22 of the distal section 14. The puller wire 24 is made of any suitablemetal, such as stainless steel or Nitinol. The puller wire 64 preferablyhas a diameter ranging from about 0.006 to about 0.010 inch.

Each compression coil 25A, 25B is made of any suitable metal, preferablystainless steel. The compression coil is tightly wound on itself toprovide flexibility, i.e. bending, but to resist compression. The innerdiameter of the compression coil is preferably slightly larger than thediameter of the puller wire. A Teflon® coating on the puller wire 24allows it to slide freely within the compression coil. The outer surfaceof each compression coil 25A and 25B is covered by a flexible,non-conductive sheath 29A and 29B (FIG. 2), e.g. made of polyimidetubing.

Because each compression coil is flexible but resists compression, itsdistal end serves as a desired location for initiation of deflection ofthe respective puller wire. The location for initiation for each pullerwire may be even with each other along the longitudinal axis of thecatheter, or the location can be different for each puller wire orpuller wire portion (used interchangeably herein). In the illustratedembodiment of FIGS. 1 and 2, both locations A and B are generallybetween the distal and proximal ends of the deflectable section 14, andthe location A is more distal than the location B which results in thecatheter having a smaller or tighter deflection DA on the side oflongitudinal portion 24A with longer compression coil 25A relative tothe side of longitudinal portion 24B with shorter compression coil 24Awhich has a larger or looser deflection DB. As shown in FIG. 1, thedeflection DA has a smaller curve with defined radius and the deflectionDB has a larger curve with defined radius.

The compression coils are anchored at their proximal end to thestiffener 21 of the catheter body 12 by proximal glue joint and at theirrespective distal end in the lumens 30 and 31 by distal glue joints.Both glue joints preferably comprise polyurethane glue or the like. Theglue may be applied by means of a syringe or the like through a holemade in the tubings of the catheter body and the deflectable distalportion 14. Such a hole may be formed, for example, by a needle or thelike that punctures the wall of the tubings which is heated sufficientlyto form a permanent hole. The glue is then introduced through the holeto the outer surface of the compression coils and wicks around the outercircumference to form a glue joint about the entire circumference ofeach compression coil.

As another feature of the present invention, at least one puller wirestrain relief compression washer 38 is provided at the distal end of thetubing 22 to anchor the mid-portion 24M. As best illustrated in FIG. 5,the washer 38 is formed with at least two through-holes 40 and 41 thatare each respectively axially-aligned with centers of the first andsecond lumens 30 and 31 of the distal section 14. Diameter of each hole40 and 41 can be up to about 14% larger than the cross-diameter of thepuller wire. During deflection, one long puller wire portion 24A or 24Bis under tension and the washer 38 is compressed against the softelastomeric distal end of the tubing 22 of the distal portion 14 due tothe puller wire tensile forces imparted by the deflection mechanismhoused in the control handle 16. Because the washer holes 40 and 41 arein alignment with the lumens 30 and 31, force vectors on eachlongitudinal portion 24A and 24B are in direct alignment with the lumens30 and 31 and the longitudinal portions 24A and 24B are subjected toonly tensile stress loading during deflection. This feature providesbetter tip deflection characteristics and reduces skew and off-plandeflection associated with prior bi-directional deflectionconfigurations. The washer 38 can be made of any suitable material,including stainless steel, nitinol or titanium.

The washer 38 may have a tab 56 at its outer circumferential edge.Washers are made in large quantities from a single acid etched sheet andthus the tab 56 is a feature used to secure the washers during themanufacturing process.

In the illustrated embodiment of FIGS. 3 and 5, a second puller wirestrain relief compression washer 39 is provided immediately adjacent anddistal of the washer 38. The washers 38 and 39 are generally identicalin structure and configuration to each other. A single or any pluralityof washers may be used to provide the desired optimal thickness tominimize or prevent deformation of the distal tip of the tubing 22during deflection by the puller wire.

With reference back to FIG. 5, the single continuous puller wire ispre-bent with the two 90 degree bends to form the portions 24A, 24B and24M. The longitudinal portions 24A and 24B are each trained into theholes 40 and 41 of the washers 38 and 39 and the lumens 30 and 31 of thetubing 22. The two 90 degree bends combined with a tight tolerancebetween the washer holes 40 and 41 relative to the cross-section orthickness of the puller wire lock the puller wire in place relative tothe tubing 22 of the distal section 14 and keep it from deforming andslipping at the 90 degree bends at the washer when tension is appliedvia the actuator and deflection mechanism.

With reference to FIG. 3, the proximal end of the tubing 23 of theconnector section 15 that slips over the distal end of the tubing 22covers the washers 38 and 39 and is bonded to the distal notched end 28of the tubing 22 by a flexible adhesive, such as a two-partpolyurethane. The central lumen 19 of the tubing 23 of the connectorsection 15 is occupied by various components that are potted therein bya suitable adhesive volume 47, e.g., epoxy. In the illustratedembodiment, the potted components include a proximal end portion 58 of asupport member 50 of the distal assembly 17, a nonconductive transitiontubing 44 for the lead wires 35 for the electrodes 27 on the distalassembly 17, and the location sensor 34 which extends from a distal endof the sensor cable 36. The location sensor 34 includes at least onesensing coil and housing for the coil (both not shown). The housing inturn is advantageously encased in a heat shrink cover or tubing 45 (bestseen in FIG. 3B) to isolate the coil from the adhesive 47. As such, anystresses transmitted into the adhesive volume 47 from torsional and/oraxial tension/compression forces acting on the support member 50 aredecoupled from the sensor 34 as the sensor is not directly bonded to theadhesive volume 47. The expansion coefficient of the adhesive-basedsensor housing and the adhesive need not match in order to preventstress cracking of the sensor housing.

The lead wires 35 connected to the electrodes 27 carried on the catheter10 pass through the nonconductive tubing 37 which passes from thecontrol handle 16, and through the central lumen 18 of the catheter body12, as shown in FIGS. 2 and 2A. The lead wires 35 then pass through thethird lumen 32 of the deflectable section 14, and through a thirdthrough-hole 43 formed in each of the washers 38 and 39. The lead wires37 then pass through a nonconductive tubing 44, e.g., constructed ofpolyimide, that extends through the connector section 15. The tubing 44has a proximal end that extends a short distance proximally of theproximal end of the connector section 15, and a distal end that isgenerally coterminous with the distal end of the connector section 15.The washer holes 43 are axially aligned with the lumen 33 of thedeflectable distal portion 14.

The sensor cable 36 extends from a proximal end of the sensor 34 andpasses through a fourth, off-axis through-hole 44 formed in the washers38 and 39, through the fourth lumen 34 of the deflectable distal portion15, through the central lumen 18 of the catheter body 12 and into thecontrol handle 16. A nonconductive tubing 46 surrounds a portion of thesensor cable that extends through the connector section 15. The tubing46, e.g., constructed of polyimide, has a proximal end that extends ashort distance proximally of the proximal end of the connector section15, and a distal end that abuts a proximal end of the sensor 34.

As illustrated in FIGS. 3 and 6, the distal assembly 17 comprises atubular structure that includes the support member 50, a non-conductivecovering 52 and a plurality of ring electrodes 27. In the disclosedembodiment, the distal assembly 17 comprises a generally straightproximal portion 58 extending axially from the connector section 15, agenerally straight portion 59 that is distal of the portion 58 andextending about 90 degrees therefrom, and a generally circular mainregion 60. Both portions 59 and 60 are generally transverse to theportion 58 and the connector section 15. As better seen in FIG. 7, theproximal region 58 (represented by X) is generally off-center of thegenerally circular main region 60. The proximal region 58 preferably hasan exposed length, i.e. not contained within the connector section 15,ranging from about 3 mm to about 12 mm, more preferably about 3 mm toabout 8 mm, still more preferably about 5 mm, but can vary as desired.

As also shown in FIG. 7, the generally circular main region 60 forms atleast a complete circle of 360 degrees, and more preferably, more thanone loop or circle, e.g., two loops or circles with inner loop 61 andouter loop 62, of about 720 degrees so that it has, for example, aspiral or conical shape. The generally circular main region 60 isgenerally transverse to the catheter body 12 and the deflectable distalportion 14, and preferably forms an angle with the catheter body rangingfrom about 80.degree. to about 100.degree., more preferably about90.degree. In the illustrated embodiment, both loops 61 and 62 generallylie within a common plane. However, it is understood that the loops 61and 62 may be arranged such that one loop is more distal than the otherloop such that the distal assembly has a generally spiral form. Thegenerally circular main region 59 has an outer diameter preferablyranging from about 10 mm to about 40 mm, more preferably from about 10mm to about 35 mm, still more preferably from about 12 mm to about 25mm, even more preferably about 20 mm. The length of the exposed distalassembly 17 (when laid out straight) from its proximal end to the distaltip, including the regions 58, 59 and 60 ranges from about 2.2-6.2″,more preferably about 3.6-5.4″, and still more preferably about4.2-4.9″. In an alternative embodiment, the distal assembly 17 furthercomprises a generally straight distal region 64 that extendssubstantially tangentially from the generally circular main region 60,as shown in FIG. 8. The region 64 may have a length ranging from about2.0 mm to about 18.0 mm, more preferably about 4.0 mm and 10.0 mm.

As shown in FIG. 3, the support rod or member 50 is elongated andextends through at least the entire length of the distal assembly 17 toprovide its shape and configuration. The support member is made of amaterial having shape-memory, i.e. that can be straightened or bent outof its original shape upon exertion of a force and is capable ofsubstantially returning to its original shape upon removal of the force.A suitable material for the support member is a nickel/titanium alloy.Such alloys typically comprise about 55% nickel and 45% titanium, butmay comprise from about 54% to about 57% nickel with the balance beingtitanium. A suitable nickel/titanium alloy is nitinol, which hasexcellent shape memory, together with ductility, strength, corrosionresistance, electrical resistivity and temperature stability.

The support member 50 has a proximal end 70 that is proximal of thedistal assembly 17. The proximal end is received and anchored in theadhesive volume of the connector section 15. In accordance with anotherfeature of the present invention, a proximal portion of the proximal end70 of the support member 50 is flattened and serrated with an unevensurface, e.g., a waffle or toothed surface, with raised and recessedregions 72 (see FIGS. 9A and 9B) to provide more bonding surface that isirregular for an adhesive bond joint that is equal or stronger than thetorsional yield strength of a puller wire with a round cross-section.Changes to the cross-section configuration (e.g., from a round form intoa more elliptical or rectangular form) and surface texture (e.g., from agenerally smooth surface to a rough or uneven surfaces) at the proximalend 70 provide superior resistance to tensile pull out orrotation/spinning of the proximal end 70 of the support member 50 pottedin the adhesive volume 47 in the connector section 15.

The extruded non-conductive cover 52 covering the support member 50 andother components of the distal assembly 17, including the lead wires 35for the ring electrodes 27, can be made of any suitable material, and ispreferably made of a biocompatible extruded plastic, e.g., polyurethaneor PEBAX 25-35 D shore hardness. In accordance with another feature ofthe invention, the cover 52 is formed with at least two lumens 53 and54, with the support member 50 extending through the lumen 53 and thelead wires 35 extending through the lumen 54. The lumen 53 for thesupport member 50 may be off-axis and on the side of the innercircumference of the generally circular region 60 so that the supportmember can better support the curvature of the region 60. The lumen 53and its diameter are also particularly sized for a tight or frictionalfit around the support member 50 to minimize or prevent free-play andmicro-movements between the support member 50 and cover 52 duringmapping or ablation procedure. The plastic material of the cover 52advantageously conforms to the shape of the support member 50 withoutrequiring heat treatment. It provides mechanical barrier and electricalisolation between the lead wires 35 and the support member 50. The cover52 extends from a distal tip end of the distal assembly 17 to near thedistal end of the connector section 15 which is sealed by a dome 74constructed of a suitable biocompatible material, such as polyurethane.A distal tip end of the distal assembly 17 is sealed by a second dome 80constructed of a suitable biocompatible material, such as polyurethane,to form an atraumatic tip end for the distal assembly. A distal end ofthe support member is surrounded by a short tubing 82, e.g., constructedof polyimide, to bond and anchor the dome 80. The material forming thedome 80 may be injected down inside the lumen of the tubing 82 andbehind the tubing 82 to prevent the dome 80 from detaching.

The distal assembly 17 carries a series of electrodes 27, including ringelectrodes, on the cover 52. The ring electrodes may be arrangedequidistance apart from each other, or in closely-spaced pairs. As usedherein, the term “ring electrode pair” refers to a pair of ringelectrodes that are arranged closer to each other than they are to theother adjacent ring electrodes. Preferably the distance between twoelectrodes 27 of an electrode pair is less than about 3 mm, morepreferably less than about 2 mm, still more preferably from about 0.5 mmto about 1.5 mm. The number of electrode can vary as desired, andpreferably ranges from about 12 to 28 ring electrodes, more preferablyabout 20 ring electrodes.

In one embodiment, the width of each electrode is generally identicalwith the exception of the most distal ring electrode which has a greaterwidth. The wider ring electrode provides a visual signal to the user ofthe location of the distal tip end when the catheter is being viewedunder fluoroscopy. Specifically, because the mapping assembly isgenerally circular, it can be difficult for the user to determine whichelectrodes are placed at a particular location in the heart. By havingone ring electrode, such as the most distal ring electrode, sizeddifferently from the other ring electrodes, the user has a referencepoint when viewing the catheter under fluoroscopy.

Regardless of the size and number of the ring electrodes, the electrodepairs are preferably approximately evenly spaced around the generallycircular main region 60. The closely-spaced electrode pairs allow formore accurate detection of near field pulmonary vein potential versusfar field atrial signals, which is very important when trying to treatatrial fibrillation. Specifically, the near field pulmonary veinpotentials are very small signals whereas the atria, located very closeto the pulmonary vein, provides much larger signals. Accordingly, evenwhen the distal assembly is placed in the pulmonary vein for mapping, itcan be difficult for the physician to determine whether the signal is asmall, close potential (from the pulmonary vein) or a larger, fartherpotential (from the atria). Closely-spaced bipoles permit the physicianto more accurately determine whether he is looking at a close signal ora far signal. Accordingly, by having closely-spaced electrodes, one isable to target exactly the locations of myocardial tissue that havepulmonary vein potentials and therefore allows the clinician to delivertherapy to the specific tissue. Moreover, the closely-spaced electrodesallow the physician to determine the exact anatomical location of theostium by the electrical signal. However, it is understood that the ringelectrodes may be configured to function in either uni-polar or bi-polarcapacity.

Multiple ring electrodes, for example, about two to 26, and morepreferably about 20, are mounted on the non-conductive cover 52 of thegenerally circular main region 60 of the ablation assembly 17. Such ringelectrodes might be desirable, for example, for mapping and/or ablation.A description of a catheter including such ring electrodes is describedin U.S. patent application Ser. No. 09/551,467, entitled “CatheterHaving Mapping Assembly,” the entire disclosure of which is incorporatedherein by reference. If desired, additional ring electrodes (not shown)could be mounted elsewhere along the distal assembly 17 and/or distalportion 14. In the illustrated embodiment of FIG. 6, a ring electrode27A is mounted at or near the distal end of the connector section 15,and a ring electrode 27B is mounted at or near the proximal end of theconnector section 15.

Connection of a lead wire to the ring electrode is preferablyaccomplished by first making a hole through a wall of the tubing onwhich the ring electrode is mounted. A lead wire is then drawn throughthe hole. The end of the lead wire is then stripped of any coating andsoldered or welded to the underside of the ring electrode, which is thenslid into position over the hole and fixed in place with polyurethaneglue or the like. Accordingly, for each ring electrode 27 carried on thedistal assembly 17, a respective hole 85 (see FIG. 6A) is made throughthe wall of the cover 52 which communicates with the lumen 54 throughwhich the respective lead wire 35 extends. For the ring electrodes 27Aand 27B carried proximally of the distal assembly 17, their lead wires40 extends through the lumen 33 alongside the sensor cable 36. For ringelectrode 27B, a hole 87 (not shown) is made through the wall of thetubing 23 which communicates with the central lumen 19 of the connectorsection 15 through the respective lead wire extends. For the ringelectrode 27A, a hole 84 (FIG. 3A) is made through the wall of thetubing 22 of the deflectable section 14 which communicates with thelumen 32 through which the respective lead wire extends. Proximal end ofeach electrode lead wire 35 is connected to a suitable connector (notshown) at the proximal end of the control handle 16. The connector isconnected to a suitable source of ablation energy (not shown), e.g.,radio frequency (RF) energy.

In use, a suitable guiding sheath is inserted into the patient with itsdistal end positioned at a desired location for mapping and/or ablation.An example of a suitable guiding sheath for use in connection with thepresent invention is the Preface™ Braided Guiding Sheath, commerciallyavailable from Biosense Webster, Inc. (Diamond Bar, Calif.). The distalend of the sheath is guided into an area of interest, for example, oneof the atria of the patient's heart. A catheter in accordance with thepresent invention is fed through the guiding sheath until its distal endextends out of the distal end of the guiding sheath. As the catheter isfed through the guiding sheath, the distal assembly 17 is straightenedto fit through the sheath. Once the distal end of the catheter ispositioned at the desired location, the guiding sheath is pulledproximally, allowing the deflectable distal portion 14 and the distalassembly 17 to extend outside the sheath, and the distal assembly 17returns to its original shape. The distal assembly 17 is then insertedinto a pulmonary vein or other tubular region (such as the coronarysinus, superior vena cava, or inferior vena cava) so that the outercircumference of each loop of the generally circular main region 60 ofthe assembly 17 is in contact with a respective circumference inside thetubular region.

The circular arrangement of the distal assembly 17 provides a stablemechanism for keeping the ring electrodes 27 in a desired location ofthe tubular region. The user can rotate the distal assembly 17 byrotating the control handle 16 to move the electrodes into contact withadjacent points along each circumference. The design of the distalassembly permits the user to more easily enable simultaneous contact ofthe ring electrodes with tissue along different circumferences of atubular region, especially where the tubular region decreases indiameter or size with distance. The catheter of the present inventionhas a dual purpose design. Large areas of the heart wall can be mappedquickly (high density mapping) with most of the loops of the distalassembly in contact with the heart wall. If the outer diameter is sizedcorrectly for the patient's anatomy, the catheter can also be used tomap the pulmonary artery where the outer circumference of each loop isin contact with the artery wall.

As will be recognized by one skilled in the art, it is easier to turnthe distal assembly in a direction such that the tip end is being pulledrather than pushed. For example, in the embodiments depicted herein,where the assembly 17 is formed in a counter-clockwise direction (whenviewed distally from the control handle 16), it is preferable to turnthe assembly in a clockwise direction. Accordingly, if desired, an arrowor other indicator (not shown) can be included on the handle or proximalend of the catheter body to indicate to the user the preferred directionfor rotating the assembly 17 in the patient's body.

Suitable designs of catheters with bi-directional deflection, includingsuitable control handles for such embodiments, are described, forexample, in U.S. Pat. Nos. 6,123,699, 6,171,277, 6,183,435, 6,183,463,6,198,974, 6,210,407, and 6,267,746, the entire disclosures of which areincorporated herein by reference.

Alternatively, a second puller wire (not shown) can be included to varyor tighten the diameter or size of the generally circular region 60 ofthe distal assembly 17. Such an arrangement is generally described inU.S. Pat. No. 5,626,136, the disclosure of which is incorporated hereinby reference. The above-referenced control handles could be used tomanipulate the second puller wire.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. It is understood that the drawings are not necessarilyto scale and that any feature of any embodiment may be incorporated inaddition to or in place of any other feature of any other embodiment.

Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest andfairest scope.

What is claimed is:
 1. A catheter comprising: an elongated tubularcatheter body with at least one lumen extending there through; adeflectable intermediate section having proximal and distal ends and atleast two off-axis lumens extending there through, the proximal end ofthe deflectable intermediate section being attached to a distal end ofthe catheter body; and a distal assembly distal of the deflectableintermediate section, the distal assembly comprising: a tubularstructure having a generally straight proximal region attached to theintermediate section, a generally circular main region generallytransverse and distal to the proximal region; an elongated supportmember extending through the generally circular main region of thedistal assembly, the elongated support member having shape memory; anon-conductive cover over at least the main region of the distalassembly; and at least one electrode carried on the generally circularmain region of the distal assembly; at least first and second washers atthe distal end of the deflectable intermediate section, each of thefirst and second washers having at least two off-axis lumens, eachaxially aligned with a respective off-axis lumen of the deflectableintermediate section; a puller wire having two proximal portions and amid-portion transverse to the two proximal portions, each proximalportion extending through a respective off-axis lumen of the deflectableintermediate section and a respective off-axis lumen of each of thefirst and second washers, the mid-portion being distal of the first andsecond washers and extending between the two off-axis lumens of thefirst and second washers; and a control handle comprising a deflectionmechanism adapted to act on at least one proximal portion of the pullerwire anchored in the control handle to deflect the deflectableintermediate section.
 2. The catheter of claim 1, further comprising aconnector section between the distal assembly and the deflectableintermediate section.
 3. The catheter of claim 2, wherein a proximal endof the support member is received in the connector section.
 4. Thecatheter of claim 2, wherein an interior of the connector section isfilled with a bonding material.
 5. The catheter of claim 4, wherein aproximal end of the support member is potted in the bonding material. 6.The catheter of claim 4, further comprising a location sensor potted inthe bonding material.
 7. The catheter of claim 6, wherein the locationsensor is surrounded in heat shrink tubing.
 8. The catheter of claim 1,wherein a proximal end of the support member is flattened.
 9. Thecatheter of claim 1, wherein a proximal end of the support member has anuneven surface.
 10. The catheter of claim 1, further comprising a firstcompression coil surrounding one of the two proximal puller wireportions and a second compression coil surrounding the other of the twoproximal puller wire portions.
 11. The catheter of claim 10, wherein thefirst compression coil has a first distal end and the second compressioncoil has a second distal end, and the first distal end is distal of thesecond distal end.
 12. The catheter of claim 1, wherein the supportmember and the nonconductive cover have a friction fit.
 13. The catheterof claim 1, wherein the nonconductive cover has at least two lumens, thesupport member extending through one of the two lumens.
 14. The catheterof claim 1, wherein each of the two off-axis lumens of each of the firstand second washers is axially-aligned with a center of a respectiveoff-axis lumen of the deflectable section.
 15. The catheter of claim 1,wherein the generally circular main region has at least two loops. 16.The catheter of claim 1, wherein the at least one electrode carried onthe generally circular main region comprises a plurality of electrodes,the plurality of electrodes ranging between about two and
 24. 17. Thecatheter of claim 1, wherein the at least one electrode carried on thegenerally circular main region comprises about 20 electrodes.
 18. Thecatheter of claim 1, further comprising at least one electrode carriedon the deflectable section.
 19. The catheter of claim 1, furthercomprising at least one electrode proximal of the distal assembly.